1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method of a semiconductor device.
2. Description of Related Art
A technology has been developed in which a portion of an insulating layer formed on a surface of an silicon carbide (SiC) semiconductor substrate is removed by etching to form an opening and a metal electrode which forms an ohmic contact with the SiC semiconductor substrate is formed in the opening. In a manufacturing method of a semiconductor device disclosed in Japanese Patent Application Publication No. 2011-176183 (JP 2011-176183 A), a silicon oxide film (SiO2 film) is first formed on the surface of the SiC semiconductor substrate. A resist layer is next formed on a surface of the silicon oxide film. Then, an opening is formed by patterning the resist layer. The silicon oxide film in an area exposed through the opening of the resist layer is next etched. The resist layer is then removed, and a metal (molybdenum) electrode layer is formed on the silicon oxide film and the surface of the SiC semiconductor layer. A resist layer is next formed on a surface of the metal electrode layer. The resist layer is then patterned, thereby forming a resist layer only on a portion to remain as an electrode. The metal electrode layer is next removed by etching, thereby allowing only the metal electrode layer protected by the resist layer to remain. Accordingly, the metal electrode is formed in the opening of the insulating layer.
In the manufacturing method described in JP 2011-176183 A, the metal electrode is formed in a whole area where the silicon oxide film (SiO2 film) is removed on the SiC semiconductor substrate. In other words, sintering is performed in a state where the metal electrode and the silicon oxide film contact with each other. As a result, metal oxides may be generated in a reaction between the metal electrode and the silicon oxide film SiO2. This may increase a contact resistance between the SiC semiconductor substrate and the metal electrode.